Fantastic resource - covers not just the 18 pounder but also the limber and the telephone wagon and limber;
http://ia600303.us.archive.org/13/items/HandbookOfThe18-pr.Q.f.Gun-LandService/Handbook18pr_final.pdf
http://www.flickr.com/photos/roblangham
Thanks for sharing the link, and for the images you uploaded. Most useful material.